1. Field of the Invention
This invention relates to inductive proximity sensors and, more particularly, to a lumped neutralization inductive proximity sensor for use in ordnance fuzes.
2. Description of the Prior Art
An inductive proximity sensor for armor defeating shell fuzes must meet requirements much more severe than those of conventional metal and mine detectors. No adjustments of any kind may be made during its use. Set back and centrifugal forces must not adversely effect the electrical characteristics of the device. The space within the ogive of the round limits the size and configuration of the primary and sensing coils. In prior art systems, neutralizing voltages are derived from a potentiometer arrangement across the primary coil. This involves the use of sliding contacts and/or electrical components such as resistors and capacitors which may be adversely effected under field conditions where shock, vibration, temperature extremes occur. In another prior art arrangement involving turn-by-turn neutralization described in U.S. Pat. No. 3,588,687, sensing and neutralizing coils must physically conform to the flux lines created by a primary coil, thereby creating additional geometrical restrictions within the fuze ogive. Accordingly, it would be extremely advantageous in a neutralization system if sliding contacts and electrical components could be avoided, and adjustments to obtain the null could be easily obtained, while at the same time having the ability to accommodate such a system within the space limitations of the fuze ogive.
Accordingly, it is an object of the present invention to provide a novel sensing coil arrangement for an inductance fuze that utilizes lumped neutralization wherein no sliding contacts or electrical components are necessary for adjustment of the coils.
A further object of the present invention is to provide a coil arrangement for an inductance fuze in which adjustments of neutralization are made by axial translations of the sensing coil, the neutralizing coil or both relative to the primary coil. An additional object is to provide a coil arrangement in lumped neutralization for an inductance proximity sensor in which the coils are easily configured to adapt to the space limitations of the ogive by maintaining a particular relationship involving the number of turns and the flux linkages in each coil.
Yet another object of the invention is to provide a sensing coil arrangement which is simple to design, inexpensive to construct and is easily incorporated into an existing fuze design.